﻿package com.kiklink.model.util;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;

public class Base64 {

	private static final char[] legalChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"

	          .toCharArray();

	 

	   

	  public static String encode(byte[] data) 
	  {

	     int start = 0;

	    int len = data.length;

	   StringBuffer buf = new StringBuffer(data.length * 3 / 2);

	 

	    int end = len - 3;

     int i = start;

	      int n = 0;

	 

	      while (i <= end) {

	           int d = ((((int) data[i]) & 0x0ff) << 16)

            | ((((int) data[i + 1]) & 0x0ff) << 8)

	                 | (((int) data[i + 2]) & 0x0ff);

	

	           buf.append(legalChars[(d >> 18) & 63]);

           buf.append(legalChars[(d >> 12) & 63]);

	           buf.append(legalChars[(d >> 6) & 63]);

	            buf.append(legalChars[d & 63]);

	 

       i += 3;

	
	          if (n++ >= 14) {

	                n = 0;

	              buf.append(" ");

	        }

	      }

	 

	     if (i == start + len - 2) {

	           int d = ((((int) data[i]) & 0x0ff) << 16)

	                 | ((((int) data[i + 1]) & 255) << 8);



	         buf.append(legalChars[(d >> 18) & 63]);

	          buf.append(legalChars[(d >> 12) & 63]);

	          buf.append(legalChars[(d >> 6) & 63]);

	          buf.append("=");

	      } else if (i == start + len - 1) {

	         int d = (((int) data[i]) & 0x0ff) << 16;

	

	          buf.append(legalChars[(d >> 18) & 63]);

	          buf.append(legalChars[(d >> 12) & 63]);

	           buf.append("==");

	      }

	

	       return buf.toString();

	  }
	  
	  
	  
	  
	  
	  
	  
	  
	  
	  
	  
	  
	  
	  
	  
	  
	  
	  public static byte[] decode(String s) {


		      ByteArrayOutputStream bos = new ByteArrayOutputStream();

		      try {

		        decode(s, bos);

		     } catch (IOException e) {

		       throw new RuntimeException();

		     }

		     byte[] decodedBytes = bos.toByteArray();

		     try {

		       bos.close();

		       bos = null;

		     } catch (IOException ex) {

		         System.err.println("Error while decoding BASE64: " + ex.toString());

		     }

		     return decodedBytes;

		   }

		    private static void decode(String s, OutputStream os) throws IOException {

		     int i = 0;

		 

		      int len = s.length();

		 

		      while (true) {

		           while (i < len && s.charAt(i) <= ' ')

		              i++;

		 

		         if (i == len)

		           break;

		

		        int tri = (decode(s.charAt(i)) << 18)

		             + (decode(s.charAt(i + 1)) << 12)

		             + (decode(s.charAt(i + 2)) << 6)

		              + (decode(s.charAt(i + 3)));

		 

		        os.write((tri >> 16) & 255);

		        if (s.charAt(i + 2) == '=')

		            break;

		        os.write((tri >> 8) & 255);

		         if (s.charAt(i + 3) == '=')

		            break;

		          os.write(tri & 255);

		 

		          i += 4;

		         }

		     }

		    private static int decode(char c) {

		      if (c >= 'A' && c <= 'Z')

		          return ((int) c) - 65;

		     else if (c >= 'a' && c <= 'z')

		          return ((int) c) - 97 + 26;

		     else if (c >= '0' && c <= '9')

		         return ((int) c) - 48 + 26 + 26;

		       else

		            switch (c) {

		         case '+':

		             return 62;

		        case '/':

		           return 63;

		          case '=':

		             return 0;

		         default:

		              throw new RuntimeException("unexpected code: " + c);

		          }

		    }
}
